The present disclosure relates to a fixing device configured to fix a toner image on a sheet and an image forming apparatus provided with the fixing device.
In the fixing device provided at an electrographic image forming apparatus, a heating member (for example, a heating roller or a heating belt) and a pressing member (for example, a pressing roller) are pressed each other to form a fixing nip. And, at the fixing nip, the sheet is heated and pressed to fix the toner image on the sheet. Such a fixing device applies a configuration that a heating source housed in the heating member heats the heating member.
For example, there exists a fixing device having a configuration that the heating member houses a plurality of heating sources which generates radiant heat so as to heat the heating member. In the fixing device, a reflecting plate arranged between the plurality of heating sources reflects the radiant heat irradiated from one of the heating sources to another of the heating sources so as to increases a heating efficiency of the heating member.
As mentioned above, since the heating member is pressed against the pressing member at the fixing nip, when the heating member is heated by the heating sources housed in the heating member, the heat escapes from the heating member to the pressing member via the fixing nip. This may require a warm-up time longer than necessary. The warm-up time means a period required to heat the heating member up to a sheet-passable temperature after the heating of the heating member is started.